arm64: exynos: don't have ARCH_EXYNOS select EXYNOS_CHIPID

arm64: exynos: don't have ARCH_EXYNOS select EXYNOS_CHIPID

Now that EXYNOS_CHIPID can be a module and is enabled by default via
ARCH_EXYNOS, we don't need to have ARCH_EXYNOS directly select it. So
remove that.

Signed-off-by: Will McVicker <willmcvicker@google.com>
Link: https://lore.kernel.org/r/20210928235635.1348330-2-willmcvicker@google.com
[krzysztof: the driver is not essential to boot and on ARMv7 it is also
 allowed to disable it]
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>